During manufacturing of a TFT LCD, after the processes of dropping liquid crystal, coating sealant and coating conductive film have been conducted on an array glass substrate and a color-film glass substrate respectively, the glass substrate has to be turned over by 180 degrees so as to be aligned with another glass substrate in a cell assembly process. After the alignment process and before curing the sealant with ultraviolet light, an operation to turn over the aligned glass substrates by 180 degrees sometimes may be required once again due to the process conditions. Therefore, the turnover operations of a glass substrate are necessary in the assembly process of a liquid crystal panel.
A conventional turnover device is shown in FIG. 4, which includes a motor 1, a tumbler 2, a turntable 20 mounted on the tumbler 2, and aligning clamps 6 and vacuum suckers 7 mounted on the turntable 20. A glass substrate is turned over by using the turntable 20, and then the glass substrate will be taken out of the device by a manipulator.
The specific operation procedure of the conventional turnover device is as follows: a glass substrate 10 is placed on the turntable 20; blowing gas is allowed to start, the glass substrates are aligned in X-axis and Y-axis with the aligning clamps 6 driven by a cylinder, and then blowing gas is stopped; a vacuum pump is turned on to operate the vacuum suckers 7 so as to suck the glass substrate 10; the glass substrate 10 is clamped by the aligning clamps 6; the tumbler 2 is driven to rotate by using the motor 1 so that the turntable 20 turns over the glass substrate 10 by 180 degrees; the manipulator accesses the turnover device from below and ascends a distance; the aligning clamps 6 release the glass substrate 10, the vacuum pump is turned off and then the vacuum suckers 7 release sucking of the glass substrate; and the manipulator waits for the glass substrate 10 to fall onto it and then descends and moves away.
It can be seen from the above operation procedure that the conventional turnover device has the following technical defects:
(1) In order to ensure that the glass substrate falls onto the manipulator stably, the manipulator has to wait for a relatively long time after it accesses the turnover device, and it will take 14 seconds to complete the whole action of taking out, which lowers the efficiency and capability of production to a certain extent.
(2) The glass substrate is held only by the sucking of the vacuum suckers distributed in a center portion of the turnover device, after it is turned over. When the sucking of the vacuum suckers is released, the glass substrate falls onto the manipulator in a freely falling manner, and although a gap between the glass substrate and the manipulator is very small, the free falling of the uncontrolled glass substrate will necessarily cause a positional deviation of the glass substrate. Such positional deviation will affect the alignment accuracy in a subsequent process and increase the possibility of failure of the products.